private void ReceiveBeaconRequest(
Header hdr,
ref Frame frame,
Byte linkQuality)
{
// see 7.3.7
bool ok = true;
ok &= (hdr.fcs.Version == Microsoft.SPOT.Wireless.IEEE_802_15_4.Mac.Frames.Version.IEEE2003);
ok &= (hdr.fcs.DstAddrMode == AddressingMode.Short);
ok &= (hdr.fcs.SrcAddrMode == AddressingMode.None);
ok &= (hdr.dstPanId == State.cBroadcastPanId);
ok &= (hdr.dstAddrShort == State.cBroadcastShortAddr);
Command.BeaconRequest msg = new Command.BeaconRequest();
if (ok && msg.ReadFromFrame(ref frame))
{
TaskBeaconRequest task = new TaskBeaconRequest();
_taskQueue.Add(task);
}
}
private void ScanRequest(TaskScanRequest task)
{
if (task == null)
{
return;
}
if (task.handler == null)
{
return;
}
UInt16 oldPanId;
lock (_state)
{ // recv thread is holding lock while processing frames. this ensures consistency
_state.scanning = true;
oldPanId = _state.macPanId;
_state.macPanId = State.cBroadcastPanId;
}
bool wasRunning = _sendReceive.Running;
if (!wasRunning)
{
_sendReceive.Start();
}
// calculate scan duration
UInt32 durationSymbols = task.scanDuration;
if (durationSymbols > 14)
{
durationSymbols = 14;
}
durationSymbols = (UInt32)(State.aBaseSuperframeDuration * ((1 << (int)durationSymbols) + 1));
// result
UInt32 unscannedChannels = 0; // bitmap
byte[] energyDetectList = null;
PanDescriptor[] panDescriptorList = null;
// set page
Phy.Status status;
Phy.PibValue pibValue = new Phy.PibValue();
pibValue.Int = task.channelPage;
_phy.SetRequest(Phy.PibAttribute.phyCurrentPage, pibValue, out status);
if (status != Phy.Status.Success)
{
unscannedChannels = task.scanChannels;
}
else
{
_state.phyChannelPage = task.channelPage;
// energyDetectList
int channelCount = 0;
if (task.scanType == ScanType.ED)
{
for (int channel = 0; channel < 27; channel++)
{
if (((1 << channel) & task.scanChannels) != 0)
{
channelCount++;
}
}
energyDetectList = new byte[channelCount];
channelCount = 0;
}
// Note: there can be a race between switching the channels here and getting the current channel when
// receiving beacons in MacReceive. This is solved through thread priorities: recv thread has higher
// priority and should not be blocked from this thread. There is still a small chance that we switch
// channel and recv assigns the new (wrong) channel, but this is by design and cannot be changed.
// iterate through all channels
for (int channel = 0; channel < 27; channel++)
{
if (((1 << channel) & task.scanChannels) != 0)
{
// set channel
pibValue.Int = channel;
_phy.SetRequest(Phy.PibAttribute.phyCurrentChannel, pibValue, out status);
if (status != Phy.Status.Success)
{
unscannedChannels |= (UInt32)(1 << channel);
channelCount++;
}
else
{
_state.phyChannelNumber = (Byte)channel;
// max value of durationSymb is 2^24, correct would be: dur*1000/rate, however this exceeds int range
// as symbolrate is multiple of 100, this works:
int durationMS = (int)(durationSymbols * 10) / (_state.phySymbolrate / 100); // symbolrate is non-zero
// perform the actual channel request
switch (task.scanType)
{
case ScanType.ED:
{
// Continuously read ED values in software for given amount of time.
#if MICROFRAMEWORK
ThreadPriority oldPriority = Thread.CurrentThread.Priority;
Thread.CurrentThread.Priority = ThreadPriority.Highest; // RT thread
#endif
Byte result = 0;
bool resultValid = false;
DateTime dtStart = System.DateTime.Now;
for (; ;)
{
Byte b;
_phy.EDRequest(out status, out b);
if (status == Phy.Status.Success)
{
resultValid = true;
if (b > result)
{
result = b;
}
}
//Thread.Sleep(1);
DateTime dtNow = System.DateTime.Now;
TimeSpan ts = dtNow - dtStart;
int elapsedMS = ts.Milliseconds + 1000 * (ts.Seconds + 60 * ts.Minutes);
if (elapsedMS >= durationMS)
{
break;
}
}
#if MICROFRAMEWORK
Thread.CurrentThread.Priority = oldPriority;
#endif
if (resultValid)
{
energyDetectList[channelCount] = result;
}
else
{
unscannedChannels |= (UInt32)(1 << channel);
}
channelCount++;
Thread.Sleep(0); // reschedule
break;
}
case ScanType.ActiveScan:
case ScanType.PassiveScan:
{
// clear any old beacon
lock (_scannedBeacons)
{
_scannedBeacons.Clear();
}
// send beacon request
if (task.scanType == ScanType.ActiveScan)
{
Header hdr = new Header();
Command.BeaconRequest cmd = new Command.BeaconRequest();
hdr.fcs.Type = Microsoft.SPOT.Wireless.IEEE_802_15_4.Mac.Frames.Type.Cmd;
hdr.fcs.DstAddrMode = AddressingMode.Short;
hdr.dstAddrShort = State.cBroadcastShortAddr;
hdr.dstPanId = State.cBroadcastPanId;
hdr.fcs.SrcAddrMode = AddressingMode.None;
hdr.seqNo = _state.macDSN++;
Frame frame = Encode(hdr, cmd);
if (frame != null)
{
_sendReceive.SendFrame(ref frame, false, hdr.seqNo);
}
Frame.Release(ref frame);
}
// wait
Thread.Sleep(durationMS);
// create result list
lock (_scannedBeacons)
{
if (_scannedBeacons.Count > 0)
{
int cntOld = 0;
int cntNew = _scannedBeacons.Count;
if (panDescriptorList == null)
{
panDescriptorList = new PanDescriptor[cntNew];
}
else
{
cntOld = panDescriptorList.Length;
PanDescriptor[] tmp = new PanDescriptor[cntOld + cntNew];
for (int i = 0; i < cntOld; i++)
{
tmp[i] = panDescriptorList[i];
}
panDescriptorList = tmp;
}
for (int i = 0; i < cntNew; i++)
{
panDescriptorList[i + cntOld] = (PanDescriptor)_scannedBeacons[i];
}
_scannedBeacons.Clear();
}
}
break;
}
case ScanType.OrphanScan:
// FIXME: not implemented
Trace.Print("Mac: ScanRequest: OrphanScan not implemented");
unscannedChannels |= (UInt32)(1 << channel);
break;
}
}
}
}
}
if (!wasRunning)
{
_sendReceive.Stop();
}
lock (_state)
{
_state.scanning = false;
_state.macPanId = oldPanId;
}
task.handler.Invoke(this, MacEnum.Success,
task.scanType, task.channelPage, unscannedChannels, energyDetectList, panDescriptorList);
}